When multiple motor vehicles approach a four-way stop intersection at the same approximate time from different directions, there is often confusion on who has the right-of-way to proceed through the intersection next. This is sometimes exacerbated by a driver of one of the vehicles allowing the others to go, even though they in reality have the legal right away at that moment. This can create a situation, especially on busy roads, where vehicles are delayed longer at the stop than is necessary, thereby impeding the flow of traffic.
This situation can be further exacerbated by someone coming to the stop who is unfamiliar with the right-of-way regulations, or who chooses to ignore them and to proceed out-of-turn through the intersection. If the driver of the vehicle having the right-of-way is not paying enough attention, or has already started to proceed through the intersection themselves, this could lead to a potentially dangerous situation, or a collision.
Systems and methods have been proposed for determining the type of intersection that a host vehicle is approaching, detecting other traffic approaching the same intersection, and determining whether the host vehicle must stop. Others propose a method for monitoring traffic signals to determine if a crossing vehicle is proceeding into the intersection in contravention of the traffic lights indication (i.e. running a red light) and alerting the driver of the host vehicle.